Stupid new movie, filling the year with TOS books on DS9's 20th anniversary.
Not making a serious complaint, so don't anybody jump down my throat *s*
I think I remember reading somewhere that TOS novels actually are the best selling Trek novels, which is why we continue to see so many in any given year. And indeed, as has already been noted the first half of every year is usually TOS heavy with the second half devoted to the 24th century series. Even this year, TNG's 25th anniversary didn't see any novels featuring the main TNG cast until June. Everything before was 23rd century. Though May's Forgotten History was actually set in both centuries, it is more a TOS novel, than anything else.
Besides, plans for a novel celebrating DS9's 20th anniversary have already been announced, so it's not like Pocket is ignoring the milestone or anything.